In the current state of the art, it is known to provide circuits having an operating point which is chosen in a linear zone of the current-voltage characteristic (i.e. the characteristic curve of current plotted against voltage). A circuit arranged in this way is known to produce responses which are substantially proportional to the input magnitude of the circuit. Such an electronic circuit may be of any kind that includes: impedence transformers: admittance transformers; voltage or current amplifiers; and/or oscillators.
However, the electronic circuits in the prior art are not satisfactory, especially when it is required to provide a circuit for a portable device having a power supply source which is of mediocre or uncertain stability. In particular, it is difficult in this case to reduce the parasitic elements in the spectrum radiated by the electronic circuit, without adding filters which increase its complexity, the dangers of thermal divergence, and its price.